Heap Buffer Overflow Vulnerability in Tmux: Critical Security Flaw Detected
Summary
OSV-2026-532: Heap-buffer-overflow in regsub. Affects tmux versions >= 7620c03b7278ed631efa98455c5e116538c23ed7, < 3badbc50e0d1c45ebfca2d2d1fad059a055584a5. Fixed in 3badbc50e0d1c45ebfca2d2d1fad059a055584a5. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
Tmux is a terminal multiplexer that allows users to manage multiple terminal sessions from a single window. It is widely used for its ability to split terminal windows, detach sessions, and maintain persistent sessions. However, like many software packages, Tmux is susceptible to vulnerabilities that can compromise its functionality and security.
Vulnerability Detail
The vulnerability identified is a heap-buffer-overflow in the 'regsub' function, which can lead to unauthorized memory access and potential crashes. This issue was reported through OSS-Fuzz, indicating that it can be exploited under certain conditions, leading to a crash state. The specific crash type is a 'Heap-buffer-overflow READ 1', which suggests that the overflow occurs when reading memory beyond the allocated buffer, potentially allowing an attacker to execute arbitrary code.
How To Fix
Minimum fixed version
3badbc50e0d1c45ebfca2d2d1fad059a055584a5
This is the first release that contains the fix.
Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can avoid using the 'regsub' function in their Tmux configurations until the patch is applied. This may limit some functionalities but can help mitigate the risk until a proper fix is implemented.
Conclusion
The heap buffer overflow vulnerability in Tmux poses a significant risk to users, potentially leading to crashes and security breaches. It is crucial to update to the patched version to mitigate these risks. Users are encouraged to utilize tools like Vulert for ongoing vulnerability monitoring.
See every vulnerability recorded for tmux →
FAQ
A heap buffer overflow occurs when a program writes more data to a buffer located on the heap than it can hold, which can lead to memory corruption and potential security vulnerabilities.
You can check if your version of Tmux is affected by comparing your installed version with the fixed version '3badbc50e0d1c45ebfca2d2d1fad059a055584a5'.
Failing to address this vulnerability can lead to crashes, data corruption, and potential exploitation by attackers, which may compromise system security.
Yes, Vulert can monitor and alert you in real-time for open-source vulnerabilities in your software using just a manifest file like package-lock.json.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
References
Related vulnerabilities
Recent vulnerabilities recorded for tmux.
